The ["deprecated"] metadata directive causes the compiler to emit code that generates a warning if you compile application code that uses a deprecated feature. This is useful if you want to remove a feature from a Slice definition but do not want to cause a hard error.
The message that follows the colon is optional; if you omit the message and use
["deprecated"], the Slice compilers insert a default message into the generated code.
You can apply the ["deprecated"] metadata directive to Slice constructs other than operations (for example, a structure or sequence definition).
